Double-sided polishing device for workpieces

Abstract

In the double-sided polishing device of the present invention, the upper platform or the lower platform has one or more through holes extending from the upper surface of the upper platform or the lower platform to the lower surface. The double-sided polishing device also includes one or more workpiece thickness measuring instruments, which can measure the thickness of the workpiece in real time from the one or more through holes during the double-sided polishing of the workpiece. A metal cylindrical member is provided on the inner circumferential surface of the upper platform or the lower platform partitioned by the through holes. The double-sided polishing device also includes a lower side window material provided at the lower part of the cylindrical member provided on the upper platform, and an upper side window material provided to cover the upper side of the through hole provided on the upper platform, or an upper side window material provided at the upper part of the cylindrical member provided on the lower platform, and a lower side window material provided to cover the lower side of the through hole provided on the lower platform.

Description

Technical Field

[0001] The invention relates to a double-sided polishing device for a workpiece. Background Art

[0002] In the manufacture of semiconductor wafers such as silicon wafers, which are typical examples of workpieces subjected to polishing, a double-side polishing process is generally used to simultaneously polish the front and back sides of the wafer in order to obtain higher-precision wafer flatness quality or surface roughness quality.

[0003] In particular, in recent years, due to the miniaturization of semiconductor elements and the increase in the diameter of semiconductor wafers, the requirements for the flatness of semiconductor wafers during exposure have become increasingly stringent. In this context, it is important to end polishing at the appropriate time, and the operator adjusts the polishing time to control it.

[0004] However, in the adjustment of the polishing time by the operator, the replacement time of the polishing auxiliary material or the deviation of the stop timing of the device is greatly affected by the polishing environment, and the polishing amount cannot necessarily be accurately controlled. As a result, it depends largely on the experience of the operator.

[0005] In response to this, the present applicant has provided a technology in which a through hole is provided in an upper platen (or a lower platen) and a measuring mechanism is used to measure the thickness of a workpiece in real time from the through hole during polishing (for example, Patent Document 1).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent document 1: Japanese Patent Application Publication No. 2019-181632. Summary of the invention

[0009] Technical problem to be solved by the invention

[0010] However, in the technology described in Patent Document 1, since the through hole is provided, dirt adheres to the surface of the window material, which reduces the measurement accuracy. In order to prevent this phenomenon, cleaning is required, which increases the running cost.

[0011] Therefore, an object of the present invention is to provide a double-side polishing apparatus for a workpiece, which can suppress adhesion of dirt in a measurement path of the thickness of the workpiece.

[0012] Solutions for solving technical problems

[0013] The gist of the present invention is as follows.

[0014] (1) A double-sided polishing device for a workpiece, comprising: a rotating platform having an upper platform and a lower platform; a sun gear disposed at the center of the rotating platform; an internal gear disposed at the outer periphery of the rotating platform; and a carrier plate disposed between the upper platform and the lower platform and having one or more holes for holding the workpiece, wherein the double-sided polishing device for a workpiece is characterized in that:

[0015] The upper platform or the lower platform has one or more through holes penetrating from the upper surface to the lower surface of the upper platform or the lower platform,

[0016] The double-sided polishing device for a workpiece further comprises at least one workpiece thickness measuring instrument, wherein the workpiece thickness measuring instrument can measure the thickness of the workpiece from the at least one through hole in real time during the double-sided polishing of the workpiece.

[0017] A metal cylindrical member is provided on the inner peripheral surface of the upper platform or the lower platform partitioned by the through hole.

[0018] The double-sided polishing device for the workpiece also includes

[0019] a lower window material provided at the lower part of the cylindrical member provided on the upper platform, and an upper window material provided to cover the upper side of the through hole provided on the upper platform, or

[0020] An upper window material is provided on the upper portion of the cylindrical member provided on the lower platform, and a lower window material is provided to cover the lower side of the through hole provided on the lower platform.

[0021] (2) The double-side polishing device for a workpiece according to (1) above, further comprising an upper member fixed to an upper portion of the upper platform or a lower member fixed to a lower portion of the lower platform.

[0022] (3) The double-sided polishing device for a workpiece according to (2) above, wherein:

[0023] The upper member and the lower member are made of stainless steel.

[0024] (4) The double-sided polishing device for a workpiece according to (2) or (3) above, wherein:

[0025] A portion of the upper member is disposed on the upper surface of the cylindrical member, and the upper window material is disposed on the upper member, or

[0026] A portion of the lower member is disposed on a lower surface of the cylindrical member, and the lower window material is provided on the lower member.

[0027] (5) The double-side polishing device for a workpiece according to any one of (1) to (4) above, further comprising one or more vent holes that communicate between the through hole and the outside.

[0028] (6) The double-side polishing device for a workpiece according to any one of (1) to (5), wherein:

[0029] The lower window material is bonded to the lower portion of the cylindrical member provided on the upper platform using a bonding layer composed of a bonding agent, or,

[0030] The upper window material is bonded to the upper portion of the cylindrical member provided on the lower platform using a bonding layer composed of a bonding agent.

[0031] (7) The double-side polishing device for a workpiece according to any one of (1) to (6), wherein:

[0032] A recess is provided on the outer circumference of the cylindrical member provided on the inner circumference of the upper platform, and an O-ring is arranged in the recess; or a recess is provided on the outer circumference of the cylindrical member provided on the inner circumference of the lower platform, and an O-ring is arranged in the recess.

[0033] Effects of the Invention

[0034] According to the present invention, it is possible to provide a double-side polishing apparatus for a workpiece that can suppress adhesion of dirt in a measurement path of the thickness of the workpiece. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a diagram showing an example of a double-side polishing apparatus for a workpiece according to an embodiment of the present invention.

[0036] Figure 2 Yes means Figure 1 Figure 1 shows the main parts of the .

[0037] Figure 3 This is a diagram showing the main part of an example of a double-side polishing apparatus for a workpiece according to another embodiment of the present invention. DETAILED DESCRIPTION

[0038] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0039] Figure 1 1 is a diagram showing an example of a double-sided polishing apparatus for a workpiece according to an embodiment of the present invention. Figure 1 As shown, the double-sided polishing device 1 includes: a rotating platform 4 having an upper platform 2 and a lower platform 3 facing the upper platform 2; a sun gear 5 disposed at the rotation center of the rotating platform 4; and an internal gear 6 disposed in a circular ring shape at the outer periphery of the rotating platform 4. Figure 1As shown, polishing pads 7 are attached to the facing surfaces of the upper and lower rotating platforms 4, that is, to the lower surface of the upper platform 2 as the polishing surface and the upper surface of the lower platform 3 as the polishing surface.

[0040] And, if Figure 1 As shown, the double-sided polishing device 1 includes a carrier plate 9 disposed between the upper platform 2 and the lower platform 3, and the carrier plate 9 has one or more holding holes 8 for holding the workpiece W. In addition, in the example shown in the figure, the double-sided polishing device 1 has only one carrier plate 9, but may also have a plurality of carrier plates 9. In the example shown in the figure, the workpiece (a wafer in this embodiment) W is held in the holding hole 8.

[0041] Here, the double-sided polishing device 1 can make the carrier plate 9 perform planetary motion by rotating the sun gear 5 and the internal gear 6, so that the carrier plate 9 revolves and rotates. That is, while supplying polishing slurry, the carrier plate 9 performs planetary motion, and at the same time, the upper platform 2 and the lower platform 3 rotate relative to the carrier plate 9, thereby making the polishing pad 7 attached to the upper and lower rotating platforms 4 and the wafer W held in the holding hole 8 of the carrier plate 9 slide on both sides, so that both sides of the wafer W can be polished at the same time.

[0042] Moreover, if Figure 1 As shown, in the double-sided polishing device 1 of the present embodiment, the upper platform 2 is provided with one or more through holes 10 penetrating from the upper surface of the upper platform 2 to the lower surface serving as the polishing surface. In the illustrated example, one through hole 10 is arranged near the center of the holding hole 8 (wafer W). In addition, in this example, the through hole 10 is provided on the upper platform 2, but it may also be provided on the lower platform 3, as long as one or more through holes 10 are provided on either the upper platform 2 or the lower platform 3. And, in Figure 1 In the example shown, although one through hole 10 is provided, a plurality of through holes 10 may be provided on the same circumference of the upper platform 2, for example. Figure 1 As shown, on the polishing pad 7 attached to the upper platform 2, a hole 11 is also penetrated at a position corresponding to the through hole 10, and is in a state of penetrating from the upper surface of the upper platform 2 to the lower surface of the polishing pad 7. In the example shown in the figure, the diameter of the hole 11 is set to be larger than the diameter of the through hole 10, but it can also be set to be smaller than or the same as it.

[0043] Furthermore, a workpiece thickness measuring instrument 12 is provided above the through hole 10, and during the double-sided polishing of the wafer W, the thickness of the wafer W can be measured in real time through the through hole 10 and the hole 11. In addition, the workpiece thickness measuring instrument 12 can be, for example, a wavelength-variable infrared laser measuring instrument. According to such a measuring instrument, the thickness of the wafer W can be measured by evaluating the interference of the reflected light on the front side of the wafer W and the reflected light on the back side.

[0044] Figure 2 Yes means Figure 1 Figure 1 shows the main parts of the .

[0045] like Figure 1 and Figure 2 As shown, in this embodiment, a metal (stainless steel in this example) cylindrical member 13 is provided on the inner peripheral surface 2a of the upper platform 2 divided by the through hole 10. In this example, a (ring-shaped) recess 14 is provided on the outer peripheral surface of the cylindrical member 13, and an O-ring (ring-shaped ring body) 15 (for example, made of rubber) is arranged in the recess 14. The O-ring 15 seals the inner peripheral surface 2a of the upper platform 2 and the cylindrical member 13 to prevent the backflow of the polishing slurry.

[0046] And, if Figure 1 and Figure 2 As shown, the double-sided polishing device 1 also includes a lower window material 16 provided at the lower part of the cylindrical member 13 provided on the upper platform 2. In the example shown in the figure, the plate-shaped lower window material 16 is arranged in a recessed portion formed in an annular shape at the lower end of the cylindrical member 13. Moreover, the upper surface of the lower window material 16 and the lower surface of the cylindrical member 13 divided by the above-mentioned recessed portion are bonded by a bonding layer 17. The lower window material 16 can be, for example, a transparent acrylic lower window material. The bonding layer 17 can be, for example, a bonding layer composed of a silicone or modified silicone bonding agent.

[0047] And, if Figure 1 and Figure 2 As shown, the double-sided polishing device 1 also includes an upper window material 18 that is arranged to cover the upper side of the through hole 10 provided on the upper platform 2. In the illustrated example, the plate-shaped upper window material 18 is arranged in a recessed portion formed in an annular shape at the upper end of the cylindrical member 13. In addition, a gasket 19 is arranged between the lower surface of the upper window material 18 and the upper surface of the cylindrical member 13 divided by the above-mentioned recessed portion, and the gasket 19 is pressed by the upper member 20 described later, so that the upper window material 18 is fixed. The upper window material 18 can be, for example, a transparent acrylic upper window material. The gasket 19 can be, for example, a rubber gasket, and the thickness of the gasket 19 is not particularly limited, but for example, a gasket of 1.0 to 3.0 mm can be used.

[0048] And, if Figure 1 and Figure 2As shown, in this example, the upper platform 2 has a protrusion 2b protruding upward at the upper part. Moreover, the double-sided polishing device 1 also includes an upper member 20 fixed to the upper part of the upper platform 2. In the example shown in the figure, the upper member 20 is composed of a portion 20a extending in the up-down direction and a portion 20b extending in the radial direction (of the through hole 10). In the example shown in the figure, the outer side surface (bolt-shaped thread groove) of the protrusion 2b of the upper platform 2 and the inner side surface (nut-shaped thread groove) of the above-mentioned portion 20a are fixed. In the example shown in the figure, the cylindrical member 13 has a portion 13a protruding radially outward at the upper end. By adjusting the thickness of the gasket 21 arranged between the protruding portion 13a and the protrusion 2b, the lower surface of the upper platform 2 is aligned with the lower surface of the cylindrical member 13, and the strength of the fixation between the upper part of the upper platform 2 and the upper member 20 can be adjusted. As Figure 1 and Figure 2 As shown, a part of the upper member (in the example shown in the figure, the part 20b) is arranged on the upper surface of the cylindrical member 13. The upper member 20 is not particularly limited, but can be made of stainless steel, for example.

[0049] Hereinafter, the effects of the double-side polishing apparatus according to this embodiment will be described.

[0050] According to the double-sided polishing apparatus 1 of the present embodiment, the through hole 10 of the upper platform 2, the hole 11 of the polishing pad 7, the lower window material 16 and the upper window material 18 are provided, and the workpiece thickness measuring instrument 12 is included. Therefore, the thickness of the workpiece (in this example, the wafer) can be measured in real time during double-sided polishing by the workpiece thickness measuring instrument 12 through the upper window material 18, the through hole 10 of the upper platform 2, the hole 11 of the polishing pad 7 and the lower window material 16. According to the double-sided polishing apparatus 1 of the present embodiment, since the upper window material 18 is provided, the adhesion of dirt (such as dust, etc.) to the lower window material 16, which is a measurement path for the workpiece thickness, can be suppressed.

[0051] Furthermore, according to the double-sided polishing device 1 of the present embodiment, a metal (stainless steel in this example) cylindrical member 13 is provided on the inner circumferential surface 2a of the upper platform 2 partitioned by the through hole 10, and a lower window material 16 and an upper window material 18 are provided on the cylindrical member 13, the lower window material 16 being provided at the lower part of the cylindrical member 13 provided on the upper platform 2, and the upper window material 18 being provided so as to cover the upper side of the through hole 10 provided on the upper platform 2. In this way, the lower window material 16 and the upper window material 18 are provided on the cylindrical member 13 instead of the platform, so that the window materials can be easily replaced, and the running cost caused by cleaning can be suppressed. Moreover, by using a strong adhesive such as a silicone or modified silicone adhesive, the backflow of the polishing slurry can be further suppressed, and the peeling of the window materials can also be suppressed. Furthermore, since the cylindrical member 13 is made of metal (stainless steel in this example), the processing accuracy is excellent, and processing that improves the measurement accuracy (such as arranging the window material horizontally) can be accurately performed.

[0052] Figure 3 FIG. 1 is a diagram showing the main parts of an example of a double-side polishing device for a workpiece according to another embodiment of the present invention. The basic structure of the double-side polishing device of the other embodiment is similar to Figure 1 The double-sided polishing device shown in FIG. 1 is the same as the double-sided polishing device shown in FIG. 1 , but the upper window material 18 (not the cylindrical member 13) is provided on the upper member 20 and one or more (one in the example shown) vents 22 (in the example shown in the figure) are provided to connect the through hole 10 and the outside (in the example shown in the figure, they are provided on the upper member 20). Figure 1 The double-side polishing apparatus shown is different.

[0053] In the example shown in the figure, the plate-shaped upper window material 18 is arranged in a concave portion formed in an annular shape at the upper end of the upper member 20. The lower surface of the upper window material 18 and the upper surface of the upper member 20 (portion 20b) divided by the concave portion are bonded by a bonding layer 23. Figure 1 Similarly to the case of FIG. 1 , the upper window member 18 can be made of, for example, a transparent acrylic upper window member, and the bonding layer 23 can be made of, for example, a silicone-based or modified silicone-based bonding agent.

[0054] According to the double-sided polishing apparatus of this other embodiment, first, the through hole 10 of the upper platform 2, the hole 11 of the polishing pad 7, the lower window material 16 and the upper window material 18 are also provided, and the workpiece thickness measuring instrument 12 is included. Therefore, the thickness of the workpiece (in this example, the wafer) can be measured in real time during double-sided polishing through the upper window material 18, the through hole 10 of the upper platform 2, the hole 11 of the polishing pad 7 and the lower window material 16. According to the double-sided polishing apparatus 1 of this other embodiment, since the upper window material 18 is also provided, the adhesion of dirt (such as dust, etc.) to the lower window material 16, which is the measurement path of the workpiece thickness, can be suppressed.

[0055] Moreover, in Figure 3 In the embodiment shown, the lower window material 16 and the upper window material 18 are not provided on the platform, but are provided on the cylindrical member 13 and the upper member 20, respectively, so that the window materials can be easily replaced, and the running cost caused by cleaning can be suppressed. Moreover, by using a strong adhesive such as a silicone or modified silicone adhesive, the backflow of the polishing slurry can be further suppressed, and the peeling of the window materials can be suppressed. In addition, since the cylindrical member 13 is made of metal (stainless steel in this example), the processing accuracy is very good, and the processing that improves the measurement accuracy (such as configuring the window material to be horizontal) can be accurately performed.

[0056] However, as a result of the inventors' research, it was found that Figure 1 and Figure 3 As shown in the figure, in the structure having the upper window material 18 and the lower window material 16, there is a possibility that turbidity will occur in the measurement path of the workpiece thickness. It is believed that the reason is that since the heat conductivity of the metal (stainless steel) component is high and the structure is sealed by the upper window material 16 and the lower window material 18, the heat generated by the sliding of the workpiece and the polishing pad during double-sided polishing is easily accumulated in the through hole 10.

[0057] Therefore, if Figure 3 In the embodiment shown in the figure, by providing one or more vents 22 that communicate with the through hole 10 and the outside, the steam or the like that causes the turbidity can be allowed to escape from the vents 22, and the heat is not accumulated from the beginning, so that the turbidity itself can be suppressed. Thus, the measurement accuracy of the workpiece thickness can be suppressed from being reduced.

[0058] Here, the double-sided polishing device 1 preferably further includes an upper member 20 fixed to the upper portion of the upper platform 2 or a lower member fixed to the lower portion of the lower platform 3. Figure 1 to Figure 3 In the example shown, the double-sided polishing device 1 includes an upper member 20 fixed to the protruding portion 2b of the upper part of the upper platform 2. In this way, the upper member 20 (or the lower member) is fixed to the upper part of the upper platform 2 (or the lower part of the lower platform 3), thereby enabling the upper window material 18 (or the lower window material 16) to be removed, and at the same time, it can be set to cover the upper side (or lower side) of the through hole. In addition, in the above-mentioned example, bolts and nuts are illustrated as a mechanism for fixing the platform and the (upper or lower) member, but it can also be other mechanisms with complementary shapes that allow the platform and the (upper or lower) member to fit each other. In addition, the upper member and the lower member are preferably made of stainless steel. The reason is that it is easier to process.

[0059] Furthermore, it is also preferred that a portion of the upper member 20 is disposed on the upper surface of the cylindrical member 13 and the upper window material 18 is provided on the upper member or a portion of the lower member is disposed on the lower surface of the cylindrical member 13 and the lower window material 16 is provided on the lower member.

[0060] Furthermore, it is preferable to provide one or more vents 22 that communicate with the through hole 10 and the outside. This is because it is possible to prevent turbidity in the through hole 10. Figure 3 In the embodiment, the through hole 22 is provided in the upper member 20, but it may be provided in other members, for example, in the cylindrical member 13. Figure 1 In the illustrated embodiment, the through hole 10 is not provided. However, in this case, for example, the through hole 10 can be provided in the cylindrical member 13 or the like.

[0061] Furthermore, it is preferred that the lower window material 16 is bonded to the lower part of the tubular member 13 provided on the upper platform 2 using a bonding layer composed of a bonding agent (e.g., a silicone or modified silicone bonding agent), or the upper window material 18 is bonded to the upper part of the tubular member 13 provided on the lower platform 3 using a bonding layer composed of a bonding agent (e.g., a silicone or modified silicone bonding agent). When a bonding agent (especially a strong bonding agent such as a silicone or modified silicone bonding agent) is used on the platform, the operation is very difficult when peeling off, but if it is a tubular member, even if a bonding agent (e.g., a silicone or modified silicone bonding agent) is used, the workability is not greatly affected when peeling off. In addition, there is no particular limitation as a silicone or modified silicone bonding agent, but for example, a super sealant manufactured by CEMEDINE Co., Ltd. can be exemplified. Alternatively, as described below, it is also possible not to use a bonding agent. That is, especially when the cylindrical member 13 or the upper member 20 (lower member) is made of stainless steel, processing is easier, so the cylindrical member 13 or the upper member 20 (lower member) is processed to be able to fit with the window material, and the window material is fit with the cylindrical member or the upper member (lower member), thereby fixing the window material and setting it to a state that is easy to replace.

[0062] Furthermore, it is preferred that a concave portion 14 is provided on the outer circumference of the cylindrical member 13 provided on the inner circumference of the upper platform 2, and an O-ring 15 is disposed in the concave portion, or a concave portion 14 is provided on the outer circumference of the cylindrical member 13 provided on the inner circumference of the lower platform 3, and an O-ring 15 is disposed in the concave portion 14. The reason for this is that the O-ring 15 seals the inner circumference of the platform 2 (3) and the cylindrical member 13, thereby preventing the backflow of the polishing slurry.

[0063] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. Figure 1 to Figure 3The case where the through hole 10 is provided on the upper platform 2 is described, but it is obvious that the present invention can be applied in the same manner even when the through hole 10 is provided on the lower platform 3. If an example is described, a metal (e.g., stainless steel) cylindrical member 13 can also be provided on the inner circumference of the lower platform 3 partitioned by the through hole 10. In addition, an upper window material 18 provided on the upper part of the cylindrical member 13 provided on the lower platform 3 and a lower window material 16 provided to cover the lower side of the through hole 10 provided on the lower platform 3 can also be included. In addition, a lower member fixed to the lower part of the lower platform 3 can also be included. The lower member can also be made of stainless steel. It is also possible that a part of the lower member is arranged on the lower surface of the cylindrical member 13, and the lower window material 16 is provided on the lower member. It is also possible that the upper window material 18 is bonded to the upper part of the cylindrical member 13 provided on the lower platform using a bonding layer composed of a bonding agent (e.g., a silicone or modified silicone bonding agent). A recessed portion 14 may be provided on the outer peripheral surface of the cylindrical member 13 provided on the inner peripheral surface of the lower table 3 , and an O-ring 15 may be disposed in the recessed portion 14 .

[0064] Description of Reference Numerals

[0065] 1-double-sided polishing device, 2-upper platform, 3-lower platform, 4-rotating platform, 5-sun gear, 6-internal gear, 7-polishing pad, 8-holding hole, 9-carrier plate, 10-through hole, 11-hole, 12-workpiece thickness measuring instrument, 13-cylindrical member, 14-recess, 15-O-ring, 16-lower window material, 17-joining layer, 18-upper window material, 19-gasket, 21-upper member, 20-washer, 22-vent, 23-joining layer.

Claims

1. A double-sided polishing device for a workpiece, comprising: A rotating platform having an upper platform and a lower platform; A sun gear, disposed at the center of the rotating platform; An internal gear, arranged on the outer periphery of the rotating platform; and a carrier plate, which is disposed between the upper platform and the lower platform and is provided with one or more holes for holding a workpiece, wherein the double-sided polishing device for the workpiece is characterized in that the upper platform or the lower platform has one or more through holes penetrating from the upper surface of the upper platform or the lower platform to the lower surface, The double-sided polishing device for a workpiece further comprises at least one workpiece thickness measuring instrument, wherein the workpiece thickness measuring instrument can measure the thickness of the workpiece from the at least one through hole in real time during the double-sided polishing of the workpiece. A metal cylindrical member is provided on the inner peripheral surface of the upper platform or the lower platform partitioned by the through hole. The double-sided polishing device for the workpiece also includes a lower window material provided at the lower part of the cylindrical member provided on the upper platform, and an upper window material provided to cover the upper side of the through hole provided on the upper platform, or an upper window material provided on the upper portion of the cylindrical member provided on the lower platform, and a lower window material provided to cover the lower side of the through hole provided on the lower platform, One or more vents are provided to communicate the through hole with the outside. 2 . The double-sided polishing device for a workpiece according to claim 1 , further comprising an upper member fixed to an upper portion of the upper platform or a lower member fixed to a lower portion of the lower platform.

3. The double-sided polishing device for a workpiece according to claim 2, wherein: The upper member and the lower member are made of stainless steel.

4. The double-sided polishing device for a workpiece according to claim 2, wherein: A portion of the upper member is disposed on the upper surface of the cylindrical member, and the upper window material is provided on the upper member, or, A portion of the lower member is disposed on a lower surface of the cylindrical member, and the lower window material is provided on the lower member.

5. The double-sided polishing device for a workpiece according to claim 3, wherein: A portion of the upper member is disposed on the upper surface of the cylindrical member, and the upper window material is provided on the upper member, or, A portion of the lower member is disposed on a lower surface of the cylindrical member, and the lower window material is provided on the lower member.

6. The double-sided polishing device for a workpiece according to any one of claims 1 to 5, wherein: The lower window material is bonded to the lower portion of the cylindrical member provided on the upper platform using a bonding layer composed of a bonding agent, or, The upper window material is bonded to the upper portion of the cylindrical member provided on the lower platform using a bonding layer composed of a bonding agent.

7. The double-sided polishing device for a workpiece according to any one of claims 1 to 5, wherein: A recessed portion is provided on the outer circumferential surface of the cylindrical member provided on the inner circumferential surface of the upper platform, and an O-ring is arranged in the recessed portion; or a recessed portion is provided on the outer circumferential surface of the cylindrical member provided on the inner circumferential surface of the lower platform, and an O-ring is arranged in the recessed portion.

8. The double-sided polishing device for a workpiece according to claim 6, wherein: A recessed portion is provided on the outer circumferential surface of the cylindrical member provided on the inner circumferential surface of the upper platform, and an O-ring is arranged in the recessed portion; or a recessed portion is provided on the outer circumferential surface of the cylindrical member provided on the inner circumferential surface of the lower platform, and an O-ring is arranged in the recessed portion.

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